David c



D. C. LARSON.

ACCELERATING MAGNET.

APPLICATION FILED AUG.26.|916. 1,309,641 Patented July 15, 1919.

2 SHEETSSHEET 1.

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INVENTOR ATTORNEY Patented July 15, 1919.

2 SHEETS-SHEET 2.

D. C. LARSON.

ACCELERATING MAGNET.

APPLICATION FILED AUG.26. 1915.

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DAVID C. LARSON, OF YONKEBS, NEW YORK, ASSIGNOB. '10 OTIS ELEVATORCOMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

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Specification of Letters Patent. Pat t d J 1 15 1919 Application filedAugust 28, 1916. Serial No. 116,972.

To all whom it may concern:

Be it known that I, DAVID C. LARSON, a citizen of the United States,residing in Yonkers, in the county of Westchester and State of New York,have invented a new and useful Improvement in Accelerating Magnets, ofwhich the following is a specification. 4

.My invention relates to an improvement in accelerating magnets whichcontrol the speed of an electric motor by cutting in or out sections ofresistance in the armature circuit of the motor.

Magnets of this nature are provided with a series of switch armscontrolling sections of resistance in the armature circuit of themotor;these switch arms should operate in a certain predetermined order, ofcourse, in order that, in bringing the motor up to speed for instance,by cutting out resistance in the armature circuit, too much resistancewill not be cut out of the circuit at one time. I have rovided a magnethaving means associated therewith which will prevent a wrong operationof the switch arms. I have shown by way of illustration four switcharms, each arm controlling a certain section of resistance, the firstarm which goes in cuts out its section of resistance, and likewise eacharm as it goes in cuts out its section of resistance, but with myarrangement until the first switch arm goes in the others cannot 0 in.By this arrangement the motor will ave been accelerated somewhat by thegoing in of the first switch arm, before any of the other arms canoperate.

Referring to the accompanying drawings illustrating my invention, Figure1 is a front elevation of the magnet, Fig. 2 is an end elevation of themagnet, Fig. 3 shows the magnet in use in an elevator system, and Fig. 4is a modification of the apparatus of Fig. 3.

The magnet is secured to a support 2 outward movement. Secured to thearm 7 is a bar 24, this bar extending across the faces of the arms 8, 9and 10, between them and the slate 1, so that these arms cannot bepulled in unless the arm 7 is first operated. The arm 7 carries at itsupper end a back contact 25 which is adapted to engage a stationarycontact 26 secured to the slate 1 by a support 27, when the arm 7 is inits outward position. It will be understood that the arms 7, 8, 9 and10, may be set at varying distances from the core 28 of the magnet, sothat it will take-more power to pull in the arm 8 than the arm 7, thearm 9 than the arm 8, etc., or they may be of varying increasingweights, for the same purpose.

I will now describe the operation of my device in connection with anelevator system, as. shown in Fig. 3. An elevator car. designated C, isadapted to 'be raised and lowered by an electric motor M, the speed ofwhich is tobe controlled by my accelerating magnet. Reversing switches Rand R are shown, to control the direction of current flow through themotor M, these switches being controlled by electromagnets E and Erespectively; these magnets in turn being controlled by the hand switchS in the car, through contacts 28 and 28. As shown in Fig. 3, if thelever of the switch S in the car be moved to the left for instance on tothe left hand contact 28, one of the electromagnets, the electromagnetE, will receive cur-rent from the main, through conductor 29, lever ofthe car switch S, left hand contact 28, conductor 30, through thewinding of the electromagnet E, conductor 31, resistance 32, conductor33, and out to The electromagnet IE will then raise its core 34 which issecured to the reversing switch R, and the contacts of the reversingswitch will be closed. A circuit may now the traced through the motor,from the main, conductor 35, contact ion reversing switch R, 39, 40,conductors 41 of the motor M, through the motor, brush 44, conductor 45,contact 46, contact 47 of the reversing switch R, conductor 48,resistance sections 49, 50, 51, 52, and out The field'circuit of themotor may be traced from the main, conductor 35, contacts 36, 37,conductor 58, conductor 59, resistance 60, conductor 61, field 62,conductor 63, and out The circuit for the winding of the acceleratingmagnet is in shunt to the motor, and may be traced from the conductor42, through conductor 64, magnet winding 20, conductor 65, conductor 45,brush 44, motor M, and brush 43 back to conductor 42. As the motor Mstarts to rotate due to the reversing switch R having been operated, itwill generate counter-electro-motive force until the same is uflicientlyhigh to pull in 'the arm 7 of the accelerating switch, and the circuitof the motor M due to the operating of the 36, contact 37 of theconductor 38, contacts and 42, brush 43 arm 7, will then be from theconductor 48,

through conductor 66, contacts 11, 16, conductor 67, and resistancesections 50, 51 and 52, and out through instead of as it originally wastraced, through the conductor 48, and resistance sections 49, 50, 51 and52. The motor will therefore accelerate. As it increases in speed thecounter electromotive force will rise until the arm 8 will be pulled in,cutting out the resistance 50; two sections of resistance will now becut out, the sections 49 and 50, and the motor will accelerate stillfurther. The arms 9 and 10 are pulled in successively, cutting out theresistance sections 51 and 52 and the motor is brought up to full speed.It will be noticed however, that unless the arm 7 is first pulled in,the other arms 8, 9 and 10, must remain out by reason of the bar 24which is in front of them. Therefore all danger of say the switch arm 9being pulled in first thereby cutting out resistance sec tions 49, 50and 51 at once, which would be injurious to the motor, is eliminated.

If when'the lever of the switch S is centered and the reversing switch Rdrops, for some reason the arm 7 of the accelerating magnet does notdrop out, I have means whereby the reversing switch cannot 'again beoperated until the arm 7 has dropped out. This means comprises thecontacts 25 and 25 and resistance 68. 'VVhen the arm 7 is in, thecontacts 25 and 25' are in engagement, and should the lever of theswitch S be operated to start the motor, it will be found that not onlydo we have a circuit through the winding of the electromagnet E, but wehave another circuit which is tapped off the conductor 31, passesthrough resistance 68 and contacts 25 and 25 and back to plus. This cutsdown the current which would otherwise flow through R is the same inprovided the windin of the electromagnet E to such an extent hat themagnet will not operate to raise its core to close the reversing switchThe operation of the reversing switch principle as the operation of theswitch R which has been described, the electromagnet E controlling itsoperation. In this case also the resistance 68 will cut down the currentin the winding of the electromagnet E in the event of the arm 7 stickingin, and it will be impossible to startthe motor until the arm 7 hasdropped. It will thus be seen that not only does this resistance 68,together with the contacts 25 and 25 prevent the motor stopped and thenstarted up again in the same direction in case the arm 7 should not dropout, but it also prevents the motor bebeing run and mg run, stopped andthen reversed unless the arm 7 has dropped out.

he operation of the mechanism shown in Fig. 4 is the same as thatdescribed in connection with Fi 3, exceptin that the circuit for the winings of the e ectromagnets E and E controlling the reversing switches isarranged in a different manner. In this instance the circuit for thewindings of these electromagnets is through the back Contact 25 of thearm 7 and through the contact 26. As the contacts 25 and 26 are never inengagement unless the arm 7 is out, it follows that the circuit for thewindings of the electromagnets E and E cannot be closed unless the arm 7is out. The advantage of this arrangement is the same as already pointedout in connection with the arrangement of Fi 3. i

What I c aim and desire to ters Patent of the United States is zl. Thecombination of a motor, means to start and stop the motor, resistanceinitially in the circuit of the motor, a plurality of arms forcuttingout said resistance in steps,

' means controlled by one of said arms simultaneously to release theother arms after the first arm has operated, and a second means carriedalso by said arm to prevent the operation of the starting means for themotor unless all the resistance is first in the circuit of the motor.

2. The combination of a motor, resistance initially in the circuit ofthe motor, an acceleratlng magnet receiving its power from thecounterelectromotive force generated by the motor, a plurality of switcharms operated by said accelerating magnet and cutting out saidresistance in steps to thereby accelerate the motor, said arms beingar-' ranged to be moved to operated position in a predetermined order, abar secured to the first arm which is to be operated and projecting intothe path of the other arms to tact carried by said tact engaged by saidcontact when the arm name to this specification in the presence 'of ismoved to operated position, and a circuit two subscribing witnesses.closed by the engagement of sitid contacts with each other to preventthe closing of the DA LARSON 5 motor circuit until said contacts havebeen Witnesses: separated. Emms'r L. GALE, J r.,

In testimony whereof, I have @signed my JAMES G. Bm'lmm...

